tap-shapefile

tap-shapefile is a Singer tap for ESRI shapefiles. Built with the Meltano Tap SDK for Singer Taps.

Quick Start

A basic pipeline is included using shapefiles found in ./data, specifically ./data/test.shp. If meltano is already installed, it should be enough to run:

meltano install

to install the required extractors and loaders, and then:

metano run tap-shapefile target-jsonl

to run the pipeline.

To Do

This is a preliminary attempt, and there are a number of features which could be included. For example:

• the projection or reference system is not currently handled, but could be
• it would be easy enough to support on-the-fly reprojection if we need our target to have a specific reference system
• we might want a composite primary key
• we might want to support state in some way, for example, to version our datasets or handle incremental loading.

Data Shape

This tap deliberately outputs data in a long format, rather than in the familiar-looking wide format we typically associate with feature classes. For example, an input shapefile that looks as follows:

id	x	y	...	geom
5bf1fd92	1	a	...	POLYGON(...)
d3395867	2	b	...	POLYGON(...)
...	...	...	...	...

Will essentially be reshaped as follows:

id	name	value	type
5bf1fd92	x	1	INT
5bf1fd92	y	a	TEXT
5bf1fd92	geom	POLYGON(( ... ))	WKT
d3395867	x	2	INT
d3395867	y	b	TEXT
d3395867	geom	POLYGON (( ... ))	WKT

This is done so that the extractor can be used more easily with existing loaders. For example, if we wanted to load the data to any of SQL Server Spatial, PostgreSQL / PostGIS, SpatiaLite, or Snowflake as spatial tables, we'd likely need to do something platform-specific in each case. With the long format, we can use a platform-specific transformation in dbt or similar later. For example, by pivoting the table about id and coercing the values as appropriate at the same time. It would be possible to make a tap that outputs data in a wide format, but converts the geographic data to one of the more popular string representations, of course.

Installation

Install from GitHub:

pipx install git+https://github.com/cmhh/tap-shapefile.git@main

Configuration

The tap expects an array called files containing objects with fields:

field	description
entity	Name of stream.
path	Path to shapefile, without extension.
id	Name of attribute to be used as a primary key.

For example, if we have a shapefiles foo/bar.shp and baz/qux.shp, each with an ID attribute named id which is unique, we might have the following config:

{
  "files": [
    {"entity": "bar", "path": "foo/bar", "id": "id"},
    {"entity": "qux", "path": "foo/qux", "id": "id"}
  ]
}

A full list of supported settings and capabilities for this tap is available by running:

tap-shapefile --about

Configure using environment variables

This Singer tap will automatically import any environment variables within the working directory's .env if the --config=ENV is provided, such that config values will be considered if a matching environment variable is set either in the terminal context or in the .env file.

Usage

You can easily run tap-shapefile by itself or in a pipeline using Meltano.

Executing the Tap Directly

tap-shapefile --version
tap-shapefile --help
tap-shapefile --config CONFIG --discover > ./catalog.json

Developer Resources

Follow these instructions to contribute to this project.

Initialize your Development Environment

pipx install poetry
poetry install

Create and Run Tests

Create tests within the tests subfolder and then run:

poetry run pytest

You can also test the tap-shapefile CLI interface directly using poetry run:

poetry run tap-shapefile --help

Testing with Meltano

Note: This tap will work in any Singer environment and does not require Meltano. Examples here are for convenience and to streamline end-to-end orchestration scenarios.

Next, install Meltano (if you haven't already) and any needed plugins:

# Install meltano
pipx install meltano
# Initialize meltano within this directory
cd tap-shapefile
meltano install

Now you can test and orchestrate using Meltano:

# Test invocation:
meltano invoke tap-shapefile --version
# OR run a test `elt` pipeline:
meltano elt tap-shapefile target-jsonl

SDK Dev Guide

See the dev guide for more instructions on how to use the SDK to develop your own taps and targets.